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Positron Emission Tomography, also called a PET scan, is a nuclear medicine exam that produces a three dimensional image of functional processes in the body. A PET scan uses a small amount of a radioactive drug to show differences between healthy and diseased tissue. PET/CT combines the fine structural detail of CT with PET's ability to detect changes in cell function. This combination allows for earlier and more accurate detection of disease than either CT or PET alone. A PET/CT can help your physician diagnose a problem, determine the best approach to treatment or monitor your progress.

What should I expect during this exam?

You will receive an intravenous (IV) injection of the radioactive substance. In some cases it may be given through an existing intravenous line.

The radioactive substance will then take approximately 60 minutes to travel through the body and be absorbed by the tissue. During this time, you will be asked to rest quietly and avoid significant movement or talking, which may alter the localization of the administered substance.

You will be positioned on the PET scanner table and asked to lie still during your exam.

Scanning takes 20 to 45 minutes.

Usually there are no restrictions on daily routine after the test. You should drink plenty of fluids to flush the radioactive substance from your body.

Are there any health risks associated with PET?

Since the doses of radiotracer administered are small, diagnostic nuclear medicine procedures result in low radiation exposure, acceptable for diagnostic exams. Thus, the radiation risk is very low compared with the potential benefits. Nuclear medicine diagnostic procedures have been used for more than five decades, and there are no known long-term adverse effects from such low-dose exposure. Allergic reactions to radiopharmaceuticals may occur but are extremely rare and are usually mild. Nevertheless, you should inform the nuclear medicine personnel of any allergies you may have or other problems that may have occured during a previous nuclear medicine exam. Injection of the radiotracer may cause slight pain and redness which should rapidly resolve. Women should always inform their physician or radiology technologist if there is any possibility that they are pregnant or if they are breastfeeding their baby.